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    <title>Document</title>
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<body>
    <script>
        var a = 10;
        ++a;
        var b = ++a + 2
        console.log(b); // 14

        var c = 10;
        c++
        var d = c++ + 2
        console.log(d); //13

        var e = 10;
        var f = e++ + ++e
        console.log(f); //21
    </script>
</body>

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